Pavement joint seals

ABSTRACT

Elongated, hollow elastomer seals particularly useful for the sealing of concrete pavement joints, bridge deck joints, etc. against intrusion by liquids and incompressible solids and embodying an elongated, preferably transversely concave top wall; an elongated bottom wall; substantially flat, elongated side walls; and an internal web structure embodying a vertical web substantially midway between the side walls with the lower end of the vertical web spaced from the bottom wall and at least two pairs of lateral webs extending from opposite sides of the vertical web, at least one of which pairs undergoes a toggle-like action when the seal is laterally compressed.

United States Patent 1 Brown 1 May 15., 1973 [54] PAVEMENT JOINT SEALS [73] Assignee: The D. S. Brown Company, North Baltimore, Ohio [22] Filed: Apr. 26, 1971 [21] Appl. No.: 137,310

7/1970 Wangerow ..94/1 8 3,485,149 12/1969 Boney ..94/18 Primary ExaminerNile C. Byers, Jr. Attorney-Johnston, Root, OKeeffe, Keil, Thompson & Shurtleff [57] ABSTRACT Elongated, hollow elastomer seals particularly useful for the sealing of concrete pavement joints, bridge deck joints, etc. against intrusion by liquids and incompressible solids and embodying an elongated, preferably transversely concave top wall; an elongated bottom wall; substantially flat, elongated side walls; and an internal web structure embodying a vertical web substantially midway between the side walls with the lower end of the vertical web spaced from the bottom wall and at least two pairs of lateral webs extending from opposite sides of the vertical web, at least one of which pairs undergoes a toggle-like action when the seal is laterally compressed.

4 Claims, 2 Drawing Figures PAVEMENT JOINT SEALS INTRODUCTION This invention concerns improvements in elastomer are particularly suitable for use in narrow construction joints. Their internal web structure and overall arrangement of the outer walls therewith provide a seal having good lateral thrust against the side walls of the joint over the range of movement of said joint during expansion and contraction of the concrete pavement. The seals herein are suitable for use as joint seals in contraction joints, longitudinal joints, and particularly in construction joints.

In recent years, hollow, elongated, elastomer strips have been developed for use as seals in concrete joints such as expansion and contraction joints in concrete roadways, air strips, bridge joints, and the like. These joint seals are inserted in a laterally compressed state into the joints to seal them against intrusion by water, solids and the like. The sides of the joint seal strips are in tight, sealing contact with the side walls of the slots or grooves forming the joint.

Joints of the aforesaid character are used inconcrete pavement or similar concrete structures to permit expansion and contraction of a given length of the concrete under varying temperature conditions. Expansion joints, which extend transversely across roadways at predetermined intervals through the full depth of the pavement, are wide enough to accommodate the lineal expansion or movement of pavement sections over the seasonal changes. Transverse contraction joints are formed less than the full depth of the pavement and control random cracking by creating transverse lines of weakness. They usually are formed by strip laid edge-' wise in wet concrete before or after the concrete is poured, or by sawing a groove across continuous strip pavement, usually after the concrete has initially set. Contraction joints usually crack the full depth along said lines of weakness as the concrete shrinks during curing or hardening or sometimes later when the pavement contracts incooler weather.

Construction joints may be transverse o'r longitudina joints. Longitudinal joints are one type of construction joint formed by the space between longitudinal strips of pavement, for example, of a two or more lane highway. The major function of longitudinal seals is to prevent foreign material from entering the longitudinal joints between the side-by-side strips or lanes of pavement. An example of a transverse construction joint is the transverse space formed between pavement sections poured on successive days.

In some highway designs, expansion joints are used in combination with contraction joints, e.g., in an arrangement of relatively widely spaced expansion joints and a plurality of contraction joints therebetween. Contraction joints allow pavement slabs to expand only to their original length. They do not accommodate relatively high orders of expansion of the concrete sections between the contraction joints with the result that some highways are designed to include expansion joints periodically in addition to the contraction joints to take up expansion of pavement which cannot be accommodated by the contraction joints between two expansion oints.

It is desirable that all such joints be sealed in order to prevent accumulation of unwanted particles such as sand, gravel, or other incompressibles from entering the open joint, filling the joint, and thereby preventing the joint from closing upon expansion of the concrete in warm weather. Joints are also sealed to prevent infiltration of water, the freezing of which in cold weather can be responsible for heaving and cracking of the pavement or damage to the joint. In highways, water in some situations may erode away the sub-soil adjacent the joint. In the case of bridges, water carrying dissolved chemicals, particularly salts used to de-ice or prevent ice on bridge decks, can be detrimental to metal and/or concrete understructures of the bridge.

It has been standard practice formany years to fill such joints with a rubber asphalt composition or similar type of caulking filler which would yield during warm weather when the width of the joint becomes smaller due to expansion of the adjacent pavement lengths. Joints having such filling materials must be repaired and replaced periodically and may require inspection and repairs at six month intervals. Caulking type fillers have several other disadvantages, a major one of which is that appreciable amounts thereon are squeezed out of the joints in warm weather when the joints are most closed and the sealing of the joints is lost when they open in colder weather.

Briefly, the subject invention concerns joint seals which are improvements over heretofore known caulking-type and elastomerjoint seals. The subject joint seals are characterized by a relatively simple internal structure having a minimum of internal webs while retaining excellent, relatively constant, lateral thrust of the side walls of the seal against the side walls of the joint over a wide range of movement of the joint with the seal in various degrees of lateral collapse. It is important that such lateral thrust be maintained throughout the entire range of movement of the joint to maintain the sealing of the joint against intrusion of water, ice or snow and dirt or other incompressible solids, the latter two of which may preclude joint movement as the joint begins to close during the period of late spring through early fall. If the joint is unable to move, the pavement sections may become sufficiently stressed so as to cause heaving or random cracking of the pavement slabs. i

Seals of the subject invention are capable of exerting a relatively constant lateral thrust against the side walls of the' joint from the 50 percent collapsed state to about one-fifth (20 percent) collapse, said percentages being based on the uncollapsed width of the seal. The seals as initially installed preferably should exert at about 20 percent collapse approximately four pounds of thrust per lineal inch of joint. All such seals have a normal width dimension greater than the widest opening expected from the joint over its anticipated movement in the field. When the seal is in its fully collapsed state, it is laterally compressed to the degree that the walls and internal webs lie against each other and preclude further lateral collapse. When the joint has opened to its widest dimension, it is preferred that the seal be at least 15-20 percent laterally collapsed, i.e., a collapsed widthof about -85 percent of the uncollapsed or normal width of the seal.

BRIEF DESCRIPTION OF THE INVENTION The subject. elongated, hollow elastomer seals have longitudinally elongated top, bottom and side walls defining a hollow, tubular-like elastomer member adapted to be laterally compressed and inserted in the laterally compressed state into joints of the character above described. The lateral or outward thrust of the side walls of the seal against the side walls of the joint is increased by an elastomer internal web structure functioning in coaction with the top, bottom and side walls to provide lines of increased localized thrust along at least the upper and lower edges of the side walls against the side walls of the joint.

The internal web structure of the subject seals comprises a vertical w'eb connected to and depending from the longitudinal midportion of a concave top wall, which preferably is in the shape of a shallow V or shallow U. The lower longitudinal edge of the vertical web is spaced from the bottom wall whereby it can move freely downwardly toward the bottom wall when the seal is laterally collapsed and the top wall takes a deeper concave configuration. The internal web structure further includes two pairs of lateral webs, each pair comprising lateral web members extending substantially symmetrically from opposite sides of the vertical web to a side wall of the seal or to a side wall and a vertical mid-wall of the seal. At least one of the two pair of webs has a downwardly diagonal orientation so that the web members thereof invert as the vertical webs movesdownwardly upon vertical collapse of the seal. This inversion produces a toggle-like action by this web pair and creates a strong lateral thrust by these webs upon inversion.

The other lateral web pairs may have a similar downwardly diagonal orientation, or they may be substantially horizontal or have an upwardly diagonal orientation. For sealing joints of relatively narrow width, for example one inch or less, one set ofinternal webs is sufficient. For wider joints, such as expansion joints or bridge joints, two, integral, side-by-side narrow seals may be used.

The bottom wall for the narrower pavement joint seal, such as construction joints and contraction joints, preferably has a relatively deep V-configuration to facilitate insertion.

DESCRIPTION OF THE DRAWING Preferred embodiments of the invention are illustrated in the drawing wherein:

FIG. 1 is an isometric view of an end fragment of a pavement joint seal useful in sealing narrow pavement joints such as construction joints and contraction joints; and

FIG. 2 is a fragmentary end elevation of a construction joint with the joint seal of FIG. I mounted therein in a laterally collapsed, joint-sealing state.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The hollow, elongated elastomer seal illustrated in FIGS. 1 and 2 embodies elongated elastomer side walls and 11 which are substantially parallel or may have a slight taper. These walls are jointed at their upper longitudinal edges with the elongated elastomer concave top wall having a shallow U- or V-configuration. In the illustrated embodiment, the top wall is the shallow V- shape provided by the top walls substantially symmet ric segments 12 and 13.

The lower edges of the side walls 10 and 11 are joined with respective longitudinal edges of an elongated elastomer bottom wall 14 which preferably has a significantly deeper or sharper V-configuration than does the top wall. The deeper V-configuration facilitates insertion of the seal in narrow pavement joints. The bottom Wall segments 15 and 16 are substantially symmetric and are joined at their lower longitudinal edges to provide the V-configuration. The latter configuratidn is deep enough to provide a longitudinal void or hollow space 17 into which the bottom portion of the vertical web 18 can move when the seal is laterally collapsed.

The internal web structure of the seal is composed of the aforesaid vertical web which is located substantially midway between the side walls 10 and 11. Its lower edge is located in a horizontal plane above the horizontal plane of the junctures of the lower, downwardly diagonally sloping lateral webs 21 and 22 with respective side walls 10 and 11 or upper portions of the bottom wall segments 15 and 16.

The vertical web thus extends downwardly from the nadir 28 of the top wall. At least two pair of lateral webs extend outwardly from the vertical web to the side walls 10 and 11 or the upper portions of bottom wall segments 15 and 16. The upper web pair 19 and 20 may slope diagonally upwardly as illustrated, may be substantially horizontal, or may slope diagonally downwardly as do the webs 21 and 22 of the lower web pair.

When the seal is laterally collapsed and placed in a pavement joint 23 between joint faces 26 and 27 of concrete pavement sections 24 and 25 (FIG. 2), the top wall assumes a deeper V-configuration and pushes downwardly the internal vertical web 18. The downwardly sloping web pair 21 and 22 invert with a togglelike action creating a significantly higher amount of lateral, outward thrust against the joint faces 26 and 27 than lateral thrust created by the upwardly diagonally sloping web pair 19 and 20. The latter web pair assumes a deeper concavity as the vertical web 18 moves downwardly and assumes a configuration as illustrated in FIG. 2, Le, substantially a U- or V-configuration. The elastic recovery forces generated in the bending of the web pairs 19, 20 and 21, 22 exerts an upward thrust via the upper portion of vertical web 18 against the nadir 28 of the top wall. This coupled with the elastic. recovery forces in the inwardly folded or bent top wall, creates a first or primary line of seal between the pavement seal and the joint faces 26 and 27 along the upper edges of the seal, which edges may be provided with laterally projecting ribs 29 and 30, preferably of tapered cross section. A secondary and equally important line of seal is that provided opposite the outer ends of the webs 21 and 22, which generate a high degree of lateral thrust via the aforesaid toggle-like action.

It will be noted particularly from FIG. 2' that the webs of the internal thrust structure have no severe bends. The disadvantages of sharp bends in web structures of elastomer seals of the character described herein have been outlined above. Accordingly the subject seals avoid disadvantages found in heretofore known seals by avoiding overstress of the webs of the internal structure through sharp bends therein when the seal is in a substantially collapsed state.

One of the distinct advantages of the internal structure of the subject seals is that all or most of the webs thereof in the state of substantially full collapse of the seal are not bent transversely into bends exceeding substantially 90. In fact, it is desirable to keep the diverging webs and apex-connecting web as straight as possible One of the disadvantages of many of the known elastomer pavement or bridge joint seals is that such seals in the full state of lateral collapse have transverse bends in many of their webs of the internal structure well above 90 and often approaching 180. The latter bends or folds cause considerable stress within the webs at the bends, particularly as they approach about 180 because such bends or folds place high amounts of stress in the web structures. Also, at high temperatures such as are common in pavements during the hot summer months, e.g., 100l40 F., the joints are in their most closed state and the seal is in its most laterally collapsed state.

Though less preferred than the embodiment illustrated, it is within the concepts of the invention to reverse the slopes of the web pairs, i.e., to have web pair 19, 20 sloping downwardly and web pair 21, 22 sloping upwardly. It is further contemplated that both web pairs may slope downwardly, whereby both invert in toggle-like fashion upon lateral compression of the seal.

in any of the forms of the invention herein, the seals should be made of good quality elastomer formulations in order that these seals retain their elastic properties with aging under environmental conditions. To this end, the elastomer composition should be an elastomer formulation which is extrudable, and which, upon vulcanization, will be resistant to deterioration and/or loss of resilience after exposure to hot and cold weather conditions, sunlight, and like elements of nature in the use thereof in joints of pavement, air strips, and thelike. Care should be exercised in selecting an elastomer formulation whereby the seal will retain its flexibility and elastic recovery force generation at the coldest temperatures to be encountered in the field. The presently best-known elastomer is neoprene, particularly the crystallization-resistant types thereof.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein disclosed being preferred embodiments for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. An elongated, elastomer joint seal having a substantially symmetrically concave top wall of V-shape, substantially parallel side walls, and a bottom wall, a vertical web substantially parallel to and substantially midway between said side walls, the upper longitudinal edge of said web being joined to the nadir of said top wall and the lower longitudinal edge of said web being spaced from said bottom wall, and lateral webs connecting said vertical web and said side walls and including a pair of opposed, diagonally downwardly sloping webs which invert in toggle-like fashion when said vertical web is pushed downwardly as said seal is laterally compressed.

2. Ajoint seal as claimed in claim 1 wherein said bottom wall is a V-shaped wall joined to the lower edges of said side walls, and said lateral webs constitute (a) said pair of opposed, downwardly sloping webs as the lower pair of webs and (b) an upper pair of opposed, upwardly sloping webs.

3. Ajoint seal as claimed in claim 1 wherein said lateral webs constitute (a) said pair of opposed, downwardly sloping webs as the lower pair of webs and (b) an upper pair of opposed, upwardly sloping webs.

4. A joint seal as claimed in claim 3 wherein said downwardly sloping webs intersect said side walls adjacent the lower edges thereof. 

1. An elongated, elastomer joint seal having a substantially symmetrically concave top wall of V-shape, substantially parallel side walls, and a bottom wall, a vertical web substantially parallel to and substantially midway between said side walls, the upper longitudinal edge of said web being joined to the nadir of said top wall and the lower longitudinal edge of said web being spaced from said bottom wall, and lateral webs connecting said vertical web and said side walls and including a pair of opposed, diagonally downwardly sloping webs which invert in toggle-like fashion when said vertical web is pushed downwardly as said seal is laterally compressed.
 2. A joint seal as claimed in claim 1 wherein said bottom wall is a V-shaped wall joined to the lower edges of said side walls, and said lateral webs constitute (a) said pair of opposed, downwardly sloping webs as the lower pair of webs and (b) an upper pair of opposed, upwardly sloping webs.
 3. A joint seal as claimed in claim 1 wherein said lateral webs constitute (a) said pair of opposed, downwardly sloping webs as the lower pair of webs and (b) an upper pair of opposed, upwardly sloping webs.
 4. A joint seal as claimed in claim 3 wherein said downwardly sloping webs intersect said side walls adjacent the lower edges thereof. 